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    <title>Document</title>
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<body>
    
</body>
</html>
<script>
    var num1 = 100;
    var num2 = 200;
    var num3 = 300;
    var num4 = 700;
   console.log("num1" + "+" +"num2" +"=" +(num1 + num2));
    console.log( "num3" + "-" + "num1"+"=" +(num3 - num1));
    console.log( "num1" + "*" + "num2"+"=" +(num1 * num2));
    console.log( "num3" +"/"+ "num1"+"=" +(num3 / num1));
    console.log("num3" + "%" + "num1" + "="+ (num3 % num1));
    //自增自减元算符  ++ --
    //console.log("num1++" + "=" + (num1++));//100
    //console.log(num1);//101
    //console.log(".........................");
   // console.log("++num2"+"="+ (++num2));//  ++在前先运算在赋值
   // console.log(num2);//201
   // console.log(++num1 + num1++);//202
   // console.log(num1++ + num1++);//201
   // console.log(num1++ + num1++ + ++num1);//304
   // console.log(num1++  + ++num2 +  ++num3 + ++num1);//704
  //  console.log(num1--);
  // console.log(++num1);
    //console.log(++num1 - --num1 + num2++ + ++num3 + num2);//703
    //符合运算符
    //console.log("num1"+ "+=" + "num2" + "=" + (num1 += num2));//300
    //console.log("num1"+ "*=" + "num2" + "=" + (num1 *= num2));//20000*/

   // console.log('num2' + '%=' + 'num4' + '=' + (num2 %= num4));

var a = 10;
var b = 20;
var c = 30;
var d = 10;
var e = "10"
var str = "张三"
//判断
console.log(a==b);
console.log(a==d);
console.log(a<=b);
console.log(a >= b);
console.log(a !=b);
console.log(a==e);//隐式转换 比较数值 不比较类型
console.log(a===e);//即比较数值 也比较数据类型
console.log(a!=e);
console.log(a !=e );//true 即比较数值 也比较数据类型
//一些特殊情况运算
console.log(a + str);//10张三
console.log(a + e);//1010
console.log(a - str);//NaN (not a number)
console.log ( typeof (a - e));//隐式转换 0
console.log(a * str);//NaN
console.log(a + b + e + c - d);//301020

</script>